Probably your best bet is a handi rifle from Hr1871.com Go there and look around and you may find something you like.
The .45/.410 chambering is popular and it seems to work pretty well. You do have to use rounds that do not use a shot cup for the .410, otherwise the shot cup will spin the shot into a very wide pattern. Those rounds are available (Federal) or you can make them yourself which is a better solution.
If you are a reloader, there are many more options available to you than if you are “Stuck with factory loads”. And I used the word “stuck” after some thought on the right word to use.
When the .45-70 was issued in 1873 to our troops there were several different types of ammo in the wagons:
1. 405 grain. Black bear are toast with this round.
2. Shotgun rounds (no shotcup) that were included so the troops could get birds and rabbits for protein in the field. It worked quite well.
3. They can also be loaded with 144 grain round ball at 405 FPS for rabbit.
4. There is another round available from Western Bullets that is 150 grain that can be driven to slightly above 2,000 FPS. Or 405 FPS if you wish for rabbit. You have to look around for the loading information but it does appear on some of the reloading forums.
All of the above have to be hand loaded as they simply aren’t on the market as ammo.
Good luck...
Thanks. Here's that 45-70 for $313.69, but a little heavy at 7 pounds.